Sunday, 17 June 2012

Lesson 6: Testing Macros in the Visual Basic Editor for Excel

Testing the VBA procedure step by step

NOTE: While you are running the macro step by step you can stop the execution at any time by clicking on the stop button in the toolbar.   VBA for Excel reset button

Testing is the most time-consuming part of any VBA project. During the development of a project you will use 20% of your time analysing and designing, 15% programming and 65% testing.

During the testing phase, you will correct bugs, typos and the logical errors. More importantly you will improve your original project, fine tune it, discover better ways to do things and add code.

In lesson 4 you have created your first macro and tested it using the "Run" button. You can also test a macro step by step.

Open Excel and a open a new workbook. Use ALT/F11 to open the Visual Basic Editor as you learned in lesson 1.

Step 1: Go to Excel and make sure that cells A1, A2 and A3 of Sheet1 are empty.

Step 2: In VBE go to the Code window of Sheet1 and copy/paste the following macro:

Sub proFirst()
        Range("A1").Value = 34
        Range("A2").Value = 66
        Range("A3").Formula = "=A1+A2"
End Sub

Step 3: Click anywhere within the macro and then press the F8 key at the top of your keyboard. VBE highlights the first line of code in yellow.

Step 4: Right-click on the small yellow arrow and see a menu appear

In lesson 4 you will learn about these precious menu items and everything else that you can do in the Code window. For now let's finish testing this macro step by step.

Step 5: Press on "F8" a second time. No line has been executed yet and if you go to Excel you will see that cells A1 to A3 are still empty. The next time you press "F8" , VBE will execute the yellow-highlighted line.

Step 6: Press "F8" a third time. The yellow-highlighted line is now "Range("A2").Value = 66". VBE has executed the previous line "Range("A1").Value = 34" has been executed so if you go to Excel (ALT/F11) you will see 32 in cell A1.

Step 7: Come back to VBE (ALT/F11) and press "F8" again. Go to Excel and see what happened in cell A2.

Step 8: Come back to VBE (ALT/F11) and press "F8" again. Go to Excel and see that there is a formula in cell A3.

Step 9: Come back to the VBE (ALT/F11) and press "F8" again, cell A1 is now selected in Excel.

Step 10: Press "F8" again. Nothing happens in Excel but "End Sub" is highlighted in yellow

Step 11: Press "F8" again. Nothing happens in Excel no more lines in VBE are highlighted in yellow.

The macro hac been tested, the test is over.
In the code change the addresses A1, A2 and A3 respectively to B1, B2 and B3.  Test the macro again. Do it as many times as you want.

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